1. Field of the Invention
The present invention relates to optical trackball devices provided as input devices for a range of electronic apparatuses, and electronic apparatuses using such optical trackball devices.
2. Background Art
Electronic apparatuses are generally designed to activate required functions by operating an input device, and thus electronic apparatuses controlled by input devices with better operability are preferred. A conventional electronic apparatus, using a personal computer as an example, is described below with reference to FIGS. 5 to 7.
FIG. 5 is a perspective view of a conventional personal computer. As shown in FIG. 5, personal computer 1 (PC 1) is a so-called laptop PC in which display unit 3 is openably attached to main unit 2. Keyboard 4 is disposed at the upper part of main unit 2, and trackball device 5 is disposed at the lower part of main unit 2. A controller (not illustrated) for controlling display unit 3, keyboard 4, and trackball device 5 is provided inside main unit 2. This PC 1 is configured to activate a required function when the user operates keyboard 4 or trackball device 5 to input required signals and the controller processes the required signals which are input.
Trackball device 5 is generally used for moving a cursor or pointer on display unit 3. The rotating direction and amount are detected when resin ball 51 protruding from main unit 2 is rotated. Ball 51 of this trackball device 5 is supported by two rollers 52 and 53 which are rotatably disposed perpendicularly to each other, as shown in a perspective view in FIG. 6 and in a top view in FIG. 7. Ball 51 is also supported by rotating member 56 (not illustrated in FIG. 6) at a position opposite that supported by rollers 52 and 53.
Rotating direction and amount are detected using output from encoders 54 and 55 attached to the above two rotatable rollers 52 and 53 respectively, as shown in the top view in FIG. 7. However, the position of ball 51 is difficult to identify in trackball device 5 embedded in conventional PC 1 when PC 1 is used in low ambient light such as at night. To solve this disadvantage, ball 51 can be made of a light-transmitting resin, and an LED can be used to light this ball 51. However, a lighting means such as an LED requires a separate component in addition to encoders 54 and 55 which are rotation-detecting means for ball 51. Consequently, an additional component or assembly step is required.